Amethyst colored gold alloy



Patented A... 1, 1942 ES PATENT] OFFICE AMETHYST COLORED GOLD ALLOY corporation No Drawing. Application July 20, 1040, Serial No. 347,758. In Germany September 28, 1935 7 Claims. (01. 148-32) The present invention relates to gold alloys of a decidedly bluish or amethyst color, which alloys possess suillcient workability that they may be employed in the manufacture of jewelry.

The present application is a continuation-im part of our earlier application Serial No. 102,046, filed September 22, 1936.

It has been known that gold combines with aluminum to form the compound of the composition of substantially AuAlz. This composition has been known as Roberts-Austen alloy or purple gold. This known alloy, however, could not be employed in the manufactur of jewelry in spite of its beautiful color as, becaus of its brittleness, it could not be bored, sawed or otherwise worked. Reference has also been made in the literature Scientific American", May 11, 1895, page 296, to an alloy consisting of 50% gold and 50% aluminum, which was stated as having a beautiful'violet color and as being soft and spongy. Recent tests, however, with this alloy show that it is not of a violet color but substantially white with only a slight violet tinge and, also, that it is not soft and spongy but substantially as brittle as the Roberts-Austen alloy.

It has now been found, in accordance with the present invention, that a gold alloy having a decidedly bluish or amethyst color may be prepared, which is sufliciently workable that it may be employed in the jewelry arts. The alloy in accordance with the present invention is sufliciently workable that it may be bored, sawed and polished so that it provides a usable medium for the jewelry art.

The alloy in accordance with the present invention, which will hereinafter be termed amethyst gold, consists substantially of 70.6% to 78.1% of gold, 19.4% to 21.4% of aluminum and 0.5% to 10.0% of zinc, the gold and aluminum being present in such alloy in a proportion of substantially 78.5 parts gold to 21.5 parts of aluminum.

In order to produce the amethyst gold alloys it has been found that it is of great importance that oxide-free starting materials be employed. Furthermore, it is preferable that the preparation of the alloy-be performed in an inert medium, for example, under nitrogen, in a vacuum or in an inert fused salt bath so that oxidation is prevented. The alloy may be prepared by meltme together the separate components or by meltirig together an AuAlz alloy and zinc or by melting together gold and a zinc aluminum alloy. The alloy in accordance with the present inventreatment.

tion may also be prepared by molding powders of the components under heat and pressure.

It has also been found that the workability and mechanical properties of the amethyst gold prepared in accordance with the present invention may be further improved by tempering such alloys by subjecting them to a prolonged heat The tempering is preferably carried out at a temperature between 200 C. and 500 C.

and in an inert medium, such as under nitrogen, in vacuum or in an inert fused salt bath. The duration of the tempering treatment may be from six to twenty-four hours, or longer.

The following compositions serve to illustrate certain modifications of the present invention, but it is in no way limitedthereto:

1. 70.6% Au, 19.7 Al; and 10% Zn 2. 74.6% Au, 20.4% Al and 5% Zn 3. 70.1%, Au, 21.4% Aland 0.5% Zn 4. 76.1% Au, 20.9% Al and 3% Zn The'latter composition is most preferred. It

a replacement for precious'stones themselves as the color thereof affords a pleasing contrast to the colors of natural gold, the various other jewelry gold alloys and platinum.

We claim: 1

1. A workable amethyst gold alloy capable of being sawed. bored and polished, consisting substantially of 70.6% to 78.1% of gold, 19.4% to 22.4% of aluminum and 0.5% to 10.0% of zinc, the gold and aluminum being present in such al- 10y in a proportion of substantially 78.5 parts of gold to 21.5 parts of aluminum.

2. A workable amethyst gold alloy capable of being sawed, bored and polished, consisting substantially of 70.6% to 78.1% of gold, 19.4% to 22.4% ofaluminum and 0.5% to 10.0% of zinc, the gold and aluminum being present in suchalloy in a proportion of substantially 78.5 parts of gold to 21.5 parts of aluminum, which alloy has been tempered at a temperature between 200 C. and 500 C. for a period of at least six hours.

3. A workable amethyst gold alloy capable of being sawed, bored and polished, consisting substantially of 76.1% of gold, 20.9% of aluminum and 3% of zinc. v

4. A workable amethyst gold alloy capable of being sawed. bored and polished, consisting substantially of 76.1% of gold, 20.9% of aluminum and 3% of zinc, which has been tempered at a temperature between 200 C. and 500 C. for a period of six to twenty-four hours.

5. A workable amethyst gold alloy capable of being sawed, bored and polished, consisting substantially of 76.1% of gold, 20.9% of aluminum and 3% of zinc, which has been tempered at a temperature between 200 c. and 500" c. for a 15 period of ten hours.

6. A jewel composed of a workable amethyst gold alloy capable of being sawed, bored and polished, consisting substantially of 70.6% to 78.1% of gold, 19.4% to 22.4% of aluminum and 0.5% to 10.0% of zinc, the gold and aluminum being present in such alloy in a proportion of substantially 78.5 parts of gold to 21.5 parts of aluminum.

'7. A jewel composed of a workable amethyst gold alloy capable of being sawed, bored and polished, consisting substantially of 76.1% of gold, 20.9% of aluminum and 3% of'zinc.

LUDWIG WEISS. JAKOB SPANNER. 

